多壁碳纳米管预分离/富集-FAAS法测定中药中Pb和Cd含量

用多壁碳纳米管对痕量铅和镉同时固相萃取,用火焰原子吸收光谱测定其含量。在最佳条件下,铅和镉的检出限分别为0.60μg·L-1、0.45μg·L-1,线性范围分别为15~300μg·L-1、10~400μg·L-1。对含有铅和镉各300μg·L-1的样品液平行测定10次,相对标准偏差(RSD)分别为4.36%和3.78%。该法简单、准确、稳定性好,将其应用于中药中铅和镉的含量测定,结果较好。     

DVD-Ag电极阳极溶出伏安法测定枸杞子中铅和镉残留

建立了利用DVD-Ag电极阳极溶出伏安法同时快速测定铅和镉的方法,并考察了I^-对电极上的铅和镉溶出分析的影响。利用该方法测定了枸杞子中铅和镉的残留含量。结果表明,优化实验条件下,在5～50μg/L浓度范围内,Pb-对电极上的铅和镉溶出分析的影响。利用该方法测定了枸杞子中铅和镉的残留含量。结果表明,优化实验条件下,在5～50μg/L浓度范围内,Pb⁽²⁺⁾和Cd(2+)和Cd⁽²⁺⁾的溶出峰电流与Pb(2+)的溶出峰电流与Pb⁽²⁺⁾和Cd(2+)和Cd⁽²⁺⁾的浓度呈线性相关,相关系数分别为0.992 3和0.995 3,Pb(2+)的浓度呈线性相关,相关系数分别为0.992 3和0.995 3,Pb⁽²⁺⁾和Cd(2+)和Cd⁽²⁺⁾的检出限分别为0.2μg/L和2.6μg/L(S/N=3)。对该方法进行了方法学考察,包括精密度、稳定性和回收率,结果均符合相关要求。枸杞子中Pb(2+)的检出限分别为0.2μg/L和2.6μg/L(S/N=3)。对该方法进行了方法学考察,包括精密度、稳定性和回收率,结果均符合相关要求。枸杞子中Pb⁽²⁺⁾和Cd(2+)和Cd⁽²⁺⁾的残留含量测定结果与经典的电感耦合等离子体质谱法(ICP-MS)一致性较好,表明该方法可用于枸杞子中铅和镉的残留量的检测。     

石墨炉原子吸收法测定黑果枸杞中铅、镉的研究

本文利用微波消解仪消化黑果枸杞样品,石墨炉原子吸收光谱法测定其中铅、镉含量。实验中条件为:铅、镉的干燥温度为80～140℃,时间为30s;铅的灰化温度为400℃,时间为15s,镉的灰化温度为300℃,时间为15s;铅的原子化温度为2000℃,时间为2s,镉的原子化温度为1500℃,时间为2s。分别用0.5%硝酸钯10μL和2%磷酸氢二铵10μL做为铅、镉的基体改进剂。实验结果表明:测定铅时在0～40μg/L的线性范围内,校准曲线线性关系为y=0.0095x+0.0059,相关性为R~2=0.9995;测定镉时在0～4μg/L的线性范围内,校准曲线线性关系式为y=0.0904x+0.0044,相关性为R~2=0.9996。铅、镉的检出限分别为0. 571μg/L和0.125μg/L;精密度分别为3.21%和2.16%;加标回收率分别为92.3%和94.6%。     

分散液液微萃取-石墨炉原子吸收光谱法测定水中痕量铅

建立了超声辅助的分散液液微萃取-石墨炉原子吸收光谱法测定水中痕量铅的新方法。采用氯仿为萃取剂、1-(2-吡啶偶氮)-2-萘酚(PAN)为螯合剂、甲醇为分散剂对铅标准溶液进行萃取富集分离,考察了萃取剂、分散剂、螯合剂、pH值及萃取时间等试验条件对萃取效果的影响。实验结果表明:在优化的试验条件下,Pb~(2+)的检出限为0.31μg/L,线性范围为0.8~30μg/L,对10μg/L的标准溶液平行测定11次,相对标准偏差(RSD)为0.31%,富集倍数达100倍。应用此方法测定了自来水和湖水中的痕量铅,加标回收率在96.4%~101.6%之间。     

电感耦合等离子体质谱测定陶瓷器皿中微晶溶出铅镉的研究

采用电感耦合等离子体质谱(ICP-MS)法,用4%乙酸溶液萃取分离Pb、Cd,对日用瓷表面微量溶出元素Pb和Cd进行了分析。对影响其测量的各种因素进行了较为详细的研究,确定了实验的最佳测定条件。结果表明,方法的检出限为0.03(Pb)和0.02μg/L(Cd),回收率为92.79%-109.09%,RSD小于3.46%。该法准确、快速、简便,应用于日用瓷中的微量溶出铅镉的测定,结果满意。     

玉米、爆米中铅、镉含量的测定

用原子吸收光谱法对玉米、爆米中污染元素铅、镉进行了测定。铅在0.00-1.80μg/L(R=0.9933)；镉在0.00-0.50μg/mL(R=0.9950）范围内均具有良好的线性关系。本方法的RSD≤4.9%，回收率在95.0-103.8%。方法快速简便，结果准确。可用于粮食中铅、镉含量的监测。     

DVD-Ag电极阳极溶出伏安法测定枸杞子中铅和镉残留

建立了利用DVD-Ag电极阳极溶出伏安法同时快速测定铅和镉的方法,并考察了I~-对电极上的铅和镉溶出分析的影响。利用该方法测定了枸杞子中铅和镉的残留含量。结果表明,优化实验条件下,在5～50μg/L浓度范围内,Pb~(2+)和Cd~(2+)的溶出峰电流与Pb~(2+)和Cd~(2+)的浓度呈线性相关,相关系数分别为0.992 3和0.995 3,Pb~(2+)和Cd~(2+)的检出限分别为0.2μg/L和2.6μg/L(S/N=3)。对该方法进行了方法学考察,包括精密度、稳定性和回收率,结果均符合相关要求。枸杞子中Pb~(2+)和Cd~(2+)的残留含量测定结果与经典的电感耦合等离子体质谱法(ICP-MS)一致性较好,表明该方法可用于枸杞子中铅和镉的残留量的检测。     

锌灰酸浸净化制氯化锌新工艺研究

研究了以炼铅厂铅锌烟灰为原料,采用盐酸浸取并以高锰酸钾氧化铁锰、锌粉置换镉铅铜两步法生产氯化锌的新方法。以锌浸出率最高、铅浸出率最低、铁锰镉铅铜除杂最彻底为考察目标,通过实验找到最佳工艺条件:40 g铅锌烟灰在由71 m L浓盐酸和130 m L水配制的混酸中在30℃条件下浸取50 min,然后加入高锰酸钾0.017 g在10℃条件下继续反应2 h,过滤后的滤液中加入锌粉0.15 g在40℃条件下反应50 min,过滤得到浓度为1.65 mol/L的氯化锌溶液。在上述工艺条件下锌的浸出率为95.4%。用制备的氯化锌溶液生产氧化锌,杂质含量满足GB/T 19589—2004《纳米氧化锌》一级品要求。     

KI-MIBK萃取原子吸收光谱法测定生活饮用水用聚氯化铝中铅和镉

采用KI-MIBK萃取火焰原子吸收光谱法测定聚氯化铝(PAC)中铅和镉。在对比了三种不同螯合剂基础上选择KI-MIBK螯合萃取体系,并探讨了酸度、掩蔽剂和螯合剂的用量等因素的影响。在最佳条件下对12个聚氯化铝样品进行测定,铅和镉的方法检出限分别为0.06μg和0.04μg,加标回收率分别为89.5%~100.6%和92.0%~100.5%。     

微波消解-石墨炉原子吸收法测定丹参中的铅镉

建立了石墨炉原子吸收法快速测定丹参药材中铅和镉元素含量的方法。利用微波消解样品,选择1.0%磷酸二氢铵和0.2%硝酸镁作为基体改进剂,用石墨炉原子吸收方法完成铅镉元素测定。结果表明,方法线性关系良好,铅和镉的相关系数分别为0.9995和0.9992;检出限分别为0.427μg/L和0.082μg/L;精密度分别为7.44%和10.97%;加标回收率分别为90.5%和104.0%。该方法是一种简便、快捷、准确的分析方法,可为丹参的进一步研究提供科学依据。     

Removal of cadmium in leachate from waste alumina beads using electrochemical technology

US Air Force uses alumina beads (aluminum oxide) as a blast media in routine maintenance operations. These spent alumina beads fail to pass the TCLP test for their cadmium contents. A chemical process consisting of leaching and electrochemical methods is investigated for the feasibility of treating the alumina beads. Dilute nitric acid was found the most effective solution for cadmium leaching. Electrochemical reduction was able to reduce cadmium content in the leachate from 180 mg/L to 15 mg/L. With consumable aluminum electrodes, electrochemical coagulation reduced the cadmium concentration to less than 1 mg/L. Electroflotation was effective for metal sludge, ferric, aluminum, and ferrous hydroxide separations with the assistance of commercial surfactants.     

REMOVAL OF CADMIUM IN LEACHATE FROM WASTE ALUMINA BEADS USING ELECTROCHEMICAL TECHNOLOGY

US Air Force uses alumina beads (aluminum oxide) as a blast media in routine maintenance operations. These spent alumina beads fail to pass the TCLP test for their cadmium contents. A chemical process consisting of leaching and electrochemical methods is investigated for the feasibility of treating the alumina beads. Dilute nitric acid was found the most effective solution for cadmium leaching. Electrochemical reduction was able to reduce cadmium content in the leachate from 180 mg/L to 15 mg/L. With consumable aluminum electrodes, electrochemical coagulation reduced the cadmium concentration to less than 1 mg/L. Electroflotation was effective for metal sludge, ferric, aluminum, and ferrous hydroxide separations with the assistance of commercial surfactants.     

Preparation of Pectin-Based Biosorbents for Cadmium and Lead Ions Removal

The optimal formation conditions of pectin-based, as well as new hybrid pectin-guar gum, biosorbents were found. The lead affinity for obtained biosorbents was very strong even in solution of pH = 1, in opposite to cadmium, which was adsorbed from solutions of pH ≥ 2. The sorption capacities in the studied conditions were about 0.6 and 0.8 mmol/g for cadmium and lead, respectively. The cadmium removal could be fast and it is almost quantitatively desorbed using 0.25 M HNO₃, while desorption of lead required 1 M HNO₃ to achieve a removal efficiency of ca. 75% from pectin-based beads. The possibility of biosorbents’ reuse was also proved. Addition of guar gum to pectin biosorbent did not change its sorption properties significantly.     

陶瓷制品铅、镉溶出量检测的不确定度分析

本文对利用原子吸收法检测陶瓷制品铅、镉溶出量的不确定度来源进行了分析     

Sorption studies of cadmium and lead ions on hybrid polysaccharide biosorbents

The sorption of lead and cadmium ions on hybrid pectin-based biosorbents containing gellan, carob, and xanthan gum has been studied. The rate constant of the metal ions’ sorption on hybrid P + X beads (analyzed with the two kinetic models: pseudo-first-order and pseudo-second–order models) is at least two times higher than obtained on other pectin-based sorbents. The Langmuir equation fits experimental data better than Freundlich model. A greater equilibrium constant B for lead(II) than cadmium(II) indicates a stronger bond between Pb(II) and pectin-based beads. Prepared hybrid materials are promising biosorbents for heavy metals’ removal from waste waters.     

Metal recovery by aged beads prepared using cell-suspension from the waste of beer fermentation broth

Lead, copper, and cadmium were adsorbed onto aged calcium alginate beads containing cell-suspension from the waste of beer fermentation broth. Beads prepared by adding 0.6% (w/v) sodium alginate into the cell suspension from the waste of beer fermentation broth and making the cell suspension drop into the 1% (w/v) calcium alginate solution were stored in the 1% (w/v) calcium chloride solution for 1 year. The specific metal uptake of the aged cell-suspension immobilized bead was 312 mg Pb²⁺, 158 mg Cu²⁺, and 112 mg Cd²⁺/g bead dry weight at pH 7.5 of the metal solution, respectively. The relation between the specific metal uptake by the aged cell-suspension immobilized beads and the equilibrium metal concentration was nonlinearly regressed and well described by the Freundlich isotherm. The specific cadmium uptake capacity of aged cell-suspension immobilized beads was between the specific cadmium uptake capacities of commercial beads Duolite GT-73 and Amberite IRA-400 and higher than those of the fresh Saccharomyces cerevisiae ATCC 834 and Saccharomyces cerevisiae ATCC 24858 immobilized beads.     

Removal of cadmium and lead from soil using aescin as a biosurfactant

Remediation of a soil contaminated with cadmium or lead was performed by a soil washing process using aescin as a biosurfactant. The removal of cadmium and lead from the soil was evaluated as a function of aescin concentration and pH in a batch process. A 30-mM aescin solution was most effective in the removal of cadmium and lead at pH 6.8. Cadmium and lead migrated from the soil to the aescin-containing aqueous phase, depending on the pH value. We found that 41% of cadmium (pH 7.8) and 25% of lead (pH 2.8) in the soil matrix migrated into a 30-mM aescin solution. Also, the complexation of aescin with cadmium and lead ions was confirmed by Fourier transform infrared spectroscopy and electrical conductivity measurements. As a result, the maximal complexation capacity of aescin with metal ions was approximately aescin/cadmium=2∶1 and aescin/lead=3∶1 on a molar basis. It was suggested that aescin may sequester cadmium and lead ions by the carboxylic and saccharide moieties. Then, the complex of aescin with cadmium or lead may migrate to the aqueous phase as the result of dispersion.     

Prediction of cadmium and zinc concentration in wheat grain from soils affected by the application of phosphate fertilizers varying in Cd concentration

Cadmium is an undesirable contaminant in phosphate fertilizer, and may represent a threat to food safety given its tendency to be taken up by plants and translocated into the edible parts. In this context, predicting wheat grain cadmium concentration from preliminary data would help to prevent exceeding the threshold values. Our study compared different approaches to estimate the concentrations of cadmium and zinc in wheat grains based on either soil solution chemistry of these elements, their quantities added to the soil and various soil parameters. Whereas the predictions based on soil solution chemistry show positive correlations between predicted and measured values of cadmium for some experimental sites, it was more difficult to predict grain cadmium concentrations in other sites. Reverse-wise, predictions based on applied cadmium and some soil parameters yielded systematically good correlations between predicted and measured values. The prediction of the concentration of zinc in wheat grains could not be achieved as its content was neither related to the measured soil solution chemistry nor to the quantities of zinc applied to the soil. We suspect that zinc interacts with the phosphate fertilizer thus obscuring the regressions for plant uptake. The prediction of grain cadmium in wheat cultures is best achieved through empirical modeling from soil parameters and soil inputs rather than through estimates of the bioavailable fractions in the soil solution.     

Metal recovery using immobilized cell suspension from a brewery

Lead, copper, and cadmium were adsorbed onto calcium alginate beads containing the cell suspension discarded from a brewery. In the cell suspension, there were many cells under lysis. The cell-suspension immobilized beads were prepared by adding 0.6% (w/v) sodium alginate into the cell suspension from the brewery and then making the cell suspension fall dropwise into the swirling 1% (w/v) calcium alginate solution. The dry weight of insoluble solid in the cell suspension was 96 g dry weight/l and the dry density of the bead containing cell suspension was 140 g dry weight/l of the bead. The specific metal uptake of the cell-suspension immobilized bead was 23.7 mg Pb²⁺, 14.3 mg Cu²⁺, and 13.4 mg Cd²⁺/g bead dry weight, respectively. The cell-suspension immobilized beads retained the initial metal-uptake capacity after 20 repeated batches of adsorption and desorption, but the fraction of metal desorbed from the beads by 1 M HCl solution was only 70% of the adsorbed metal. The beads, which had been contained for 14 successive days in the 0.5% (w/v) CaCl₂ solution at 4 °C just after 20 cycles of adsorption/desorption, retained the initial metal-uptake capacity after 30 repeated cycles, and more than 90% of the copper and cadmium adsorbed on the beads was desorbed by the 1 M HCl solution.     

Removal of lead,cadmium and zinc from aqueous solutions by precipitation with sodium Di‐(n‐octyl) phosphinate

Sodium di‐(n‐octyl) phosphinate (NaL) was used as a precipitating agent to remove heavy metals from aqueous nitrate solutions. Cadmium, zinc and mixtures of lead, cadmium and zinc were precipitated in the form of PbL_2(s), CdL_2(s), and ZnL_2(s). Lowering the pH of the feed solution reduced the removal of the metals as some of the phosphinate precipitated in the acid form as HL_(S). The removal of lead, cadmium, and zinc, from a solution containing the three metals gave a selectivity in the order Zn > Pb > Cd. Predictions of an equilibrium‐constant model, using measured solubility products of the precipitates and literature values of stability constants, gave metal removals, loss of precipitating agent, and equilibrium pH in good agreement with measured values.